This invention relates generally to a protective assembly in which a radioactive substance can be transferred and a related method of so transferring the substance and more particularly, but not by way of limitation, to a radioactivity shielding container and method of using the same in transferring a radioactive substance directly to a receiver without substantially disassembling the container.
In the medical industry liquid radioactive tracer substances are used for various purposes. Such tracers are often transported in receptacles which are packaged to provide some degree of radioactivity shielding. In the oil industry, particulate radioactive tracer substances have been used in fracturing activities to detect where fractures have been made. At the present time, liquid radioactive tracer substances are also being used in the oil industry for a similar purpose.
Some advantages of using such liquid tracers in the oil industry are that the tracers can be pumped directly into the well at high pressures with conventional pumping equipment, the tracers can be accurately volumetrically metered, and the tracers can be shipped in concentrated forms so that small shipping packages can be used.
These usages, both in the medical and oil industries, bring people, equipment and the surrounding environment into association with, and thus into potential exposure to and contamination from, the radioactive substances, which substances can be very absorbent in liquid form and which substances can have large radiation exposure levels associated with small amounts in concentrated form. Furthermore, the used packaging, which can have a significant residue of the tracer or otherwise be contaminated, can also provide a health risk if it is not properly constructed and handled. In view of these risks of radiation exposure and contamination, the packaging in which such substances are transported from their points of being charged with the radioactive substances to their points of being discharged of the substances must be carefully manufactured and handled. Depending upon the nature of the use to which the packaging is to be put, such packaging may even need to meet governmental regulations, such as of the type promulgated by the United States Department of Transportation.
Two types of packaging, one used in the medical industry and the other used in the oil industry, are known to me. One type includes a syringe body which is concentrically received within a removable cylindrical lead jacket. This syringe body and jacket are placed in a carrying housing having a removable cap which is used to close the open end of the housing once the syringe and jacket assembly are placed inside the housing.
A shortcoming of this type of packaging is that the syringe body, which is made of a material that does not provide any significant radioactivity shielding, can be easily separated from the protective cylindrical sleeve during use. Furthermore, the syringe body, even if it is not removed from the protective sleeve, must be handled during use to remove it from the outer housing after the cap is removed from the housing. One also needs to handle the syringe body in connecting it to the object into which the radioactive substance is to be transferred.
The other type of packaging of which I am aware includes a lead carrying housing having a cavity into which a glass bottle, filled with the radioactive substance, is received. The glass bottle has a screw-on cap associated with it, and the carrying housing has a suitable lid associated with it. This type of packaging is potentially more hazardous than the previously mentioned packaging because it has no protective sleeve surrounding the bottle once it is removed from the lead housing, and such removal is necessary in pouring the radioactive substance from the bottle. This requires that a person either directly handle the unshielded bottle in removing it from the housing and in removing its cap and pouring the substance from the bottle or indirectly handle the bottle through some type of mechanical manipulating device, which type of device is likely less sensitive in its control of the bottle than direct human handling would provide, whereby the contents of the bottle can be easily and inadvertently spilled. Furthermore, such mechanical manipulation devices are not always available at a well site where radioactive tracer is to be transferred for injection into a well during a fracturing process, for example.
In view of the foregoing shortcomings of these two prior art containers known to me, there is the need for a durable safety container which is constructed and used in such a way that inadvertent or unnecessary radioactivity exposure or contamination of humans, equipment and the environment can be avoided or minimized. Such a container should provide a receptacle for receiving the radioactive substance and a protective casing which is not to be separated from the receptacle during normal usage. Such a container should be designed so that minimal handling is required in either charging or discharging a radioactive substance into or out of the container. Such a construction minimizes the risk of exposure or contamination of personnel, equipment and the environment. Such a container should be constructed of components that can be easily manufactured in compliance with pertinent governmental regulations, such as those promulgated by the Department of Transportation. There is also the need for an associated method of safely transferring a radioactive substance with such a container.